A28-year-old male is admitted to the burn unit 2 hours after receiving second- and third-degree burns over 50% of his body surface in an industrial explosion. abnormal vital signs include low blood pressure and tachycardia. lab results show a high hematocrit due to:

Fluid movement out of the vascular space

The inflammation that caused by the injury also cause edema in many places, makes the fluid comes from vascular into interstitial space. 
Since the skin is damaged in a burned patient, the patient might lose many fluids from their burned skins later on. 
These conditions can cause dehydration that ends up will cause an increase in hematocrits level.